The Study on Titanium Dioxide-Silica Binary Mixture Coated SrAl2O4: Eu2+, Dy3+ Phosphor as a Photoluminescence Pigment in a Waterborne Paint.

After proper stimulation, long afterglow phosphors formulated as pigment in waterborne paints can emit light after the removal of the excitation light source. The encapsulation of SrAl2O4: Eu2+, Dy3+ phosphor by TiO2 and SiO2 individually, and in combination by a precipitation method was studied. The water resistance and photoluminescence behavior of the coated phosphors as a pigment for potential use in waterborne photoluminescence paints were evaluated. It revealed that the TiO2- SiO2 content coating layer was precipitated on the studied phosphor successfully. The higher trend of the TiO2 for coating on the phosphor when compared with the SiO2 was observed from EDS spectra. The SEM micrographs showed a continuous and uniform SiO2-TiO2 layer on the coated phosphor. Based on XRD results, the existence of the TiO2 in the coating layer had beneficial effect on the average crystallite size values. The pH solution versus time showed that the availability of the TiO2 in coated layer improved water resistance of the coated phosphor, although, in comparison with SiO2, it was less effective. The coated phosphor with TiO2 had the minimum afterglow brightness decay and consequently, it was recommended as a suitable pigment for waterborne photoluminescence paints.